Can you play audio cds that you've burned on cdr at your playstation ? If so, then I assume that there is no modchip installed inside this psx. Btw, I never heard that "all psx" comes with an installed modchip, because a modchip is a pirate product and using copies is illegal, if you don't own the original.

Anyway, have a look at: http://www.cdrom-guide.com/ubb/Forum19/HTML/017810.html , this might help you too.

ps. the modchip isn't responsible for the color of cds recognized properly by the build in reading unit, it's the laser-unit and it's adjustment.